This invention relates generally to the art of alloys, and more particularly, to the art of diffusion modification of surface areas formed with metallic parts.
Metallic components have conventionally been modified over the course of prior art to provide superior characteristics on the surface areas thereof while the internal areas are substantially unaffected. Examples of such processes include galvanizing wherein metallic components are coated with zinc or other alloys to enhance resistance to surrounding environments. Another example of such prior art techniques involves the treatment of aluminum by an anodizing technique to form a thin layer of oxide, and to also provide enhanced resistance to surrounding environments.
More sophisticated techniques have involved the diffusion of various metallic substances into the surface of formed metallic parts. Traditionally, this has been carried out within heated environments utilizing various heating elements where entire environments are heated to a temperature sufficient to effect diffusion of metals into formed metallic parts. One such process is the retort method wherein a metallic part is welded within a retort contained in the metallic substance to be diffused into the surface thereof. Generally, this involves a slow heating to approximately 2100xc2x0 F., followed by a long, slow cooling. Techniques known as the pack method and blanker method are similar, but also require long heating and cool down periods with substantial volumes of material, including the part and metallic substance effecting the change in the part. Normally such techniques involving the slow heating and cooling bring about substantial changes, not only in the surface of the metallic parts, but the inner volume areas where grain growth and refinement take place as a natural consequence of such heating.
It is thus an object of this invention to provide an improved process for surface modification of formed metallic parts.
It is a further object of this invention to modify the surface of formed metallic parts by diffusion of metals which will provide improved corrosion resistance and improved resistance to physical wear and abrasion.
It is a further object of this invention to provide such modification by an improved process which does not result in substantial grain growth or refining of the interior volume of such formed metallic parts.
It is a further and yet more particular object of this invention to provide such an improved process which has a time cycle substantially less than that encountered in the prior art.
These as well as other objects are accomplished by a process for diffusing metal into the surface of a formed metallic part by surrounding said formed metallic part within an environment of an insulator material having a desired metal dispersed therein. Microwaves are directed to the environment to heat the formed metallic part and the surrounding environment to a temperature sufficient to cause diffusion of the desired metal into surface portions of the desired part.